An estimated half a million women are being transported to Western Europe by sex traffickers every year. It's a multi-million pound business where, for the traffickers, the rewards are high and the risks are low. But, for the girls, the consequences are brutal and potentially dangerous. Following a route which begins in the former Soviet Republic of Latvia and leads to Denmark, Ireland and the UK, Sue Lloyd-Roberts uncovers a murky, cruel world in which employment agencies seduce young women with false promises, unscrupulous pimps abuse them and the police and judiciary turn a blind eye to this contemporary form of slavery.